Process of cleaning metallic surfaces.



.No. 821,622. PATENTED MAY 29, 1906.

T.-A. EDISON. I PROCESS OF CLEANING METALLIC SURFACES.

APPLICATION FILED JUNEZ9.1904.

wilt-mesa a awuc nfiofa b M 16) cm a as: H I 2 J I AM UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF LLEWELLYN PARK, NEW JERSEY.

PROCESS OF CLEANING METALLIC SURFACES.

Specification of Letters Patent.

' Patented May 29, 1906.

Application filed June 29, 1904- .Serial No. 214,652.

To all LU/Llfli'bjfi 77mm concern:

Be it known that I, THOMAS A. EDISON,

residing at Llewellyn Park, Orange, county of.

Essex, State of New Jersey, have invented a certain new and useful Process of Cleaning Metallic Surfaces, of which the following is a description.

My invention relates to an improved process of cleaning long continuous metallic surfaces or strips preliminary to subsequent treatment by which the surface is coated with another metal or materialas, for example, in processes of electroplating, amalgamating, tinning, galvanizing, enameling, &c. In treating such surfaces in a continuous manner it is desirable to Miss the same continuously through a suita le bath, which may be either a solvent or electrolyte, by which the oil, grease, dirt, oxid, &c., Will be removed from the surface of the material, so as to leave a clean surface for receiving the coating referred to, in order that the coating maybe free from bare spots and adhere tenaciously. The impurities thus removed from the material, especially oil and grease, float upon the surface of the bath, so. that the strip as it leaves the bath must ordinarily p2 ss through such impurities, which will thereby contaminate the clean surface and necessitate a subsequent cleaning operation.

My invention has for its object the prevention of such contamination, the dispensing with a second or secondary cleaning 0 eration, and the securing ofa perfectly 0 can itrip1 by passing the same through a single It may be em loyed in any continuous cleansing or picking process, but is preferably applied to a process wherein the strip to be cleaned is em 10;, ed asa cathode in an electrodepositionath and is opposed to an anode not attacked by the electrolyte and where there is no metal or substance in the solution which can be plated out, whereby the passage of a current of sufficient density results in the generation of large quantities of hydrogen gas on the surfaces to be cleaned,

which gas in detaching itself from such surfaces mechanically strips off the foreign matter, so as to leave an absolutely clean surface.

. This result is largely facilitated by reason of the fact that the oil, grease, dirt, and other foreign material is more or less porous, so thatiithe gas has an opportunity of forcibly detaching itself from the surfaci to carry the foreign material with it.

This result is almost entirely mechanical, although there may be, of course, a slight reduction of any oxid present by potassium or hydrogen gas. I find, however, that if an iron object having a more or loss rusty surface is subjected to this treatment the hydrogen gas mechanically separates the oxid, which floats off on the electrolyte Without being reduced to any appreciable extent.

As I have already indicated, my improved process may be used in many arts and for the preliminary treatment of many different metals; but it has been designed particularly for use for cleaning long endless strips of thin sheet-iron which are to be subsequently nickel-plated for use in the make-up of my improved storage battery.

In the accompanying drawing 1 illustrate an apparatus suitable for carrying out my improved process. The drawing in question is a vertical sectional view.

In the drawing a suitable tank 1 is shown, formed of any desired material and provided with rollers 2 2, preferably insulated from the tank, and over which passes the endless strip 3, whose surfaces are to be cleaned. The support for the central roller, as shown, is preferably protected by an insulating-tube of soft rubber or other material not affected by the solution. The strip 3 leaves the solution through a tube 4, made preferably of glass or hard rubber, extending below the surface of the. solution, so that any oil, grease, or dirt which may float on the surface will be ke t free of the strip, as will be understood. illustrate two anodes 5 5, which are composed of some material not attacked by electrolysis in the solution. The electrolyte used is preferably a ten-per-cent. solution of 03 cnid of potassium, and when such an electrolyte is used the anodes are formed, preferably, of pure carbon, such as graphite. Graphite I find is preferable over other forms of carbon, owing to its absolute insolubility in an alkaline solution when subjected to electrolysis. These anodes are arranged on opposite sides of a portionof the strip, so that the two faces thereof will be simultaneously cleaned. Current is fu nished from a platm'g-dynamo or other source of supply 6, and the connections are such that the stri '3 or other article to be cleaned will act as t e cathode. With such an apparatus the passage of the current between the anodes 5 and the strip-like cathode or other object to be cleaned results simply in the generation of oxygen at the anodes, having no effect 1. The process of cleaning continuous me thereon, and of large quantities of hydrogen tallic strips which consists in passing the at the surface of the cathode, the current strip through a suitable cleansing-bath and used being sufficient to generate hydrogen in removing the strip from said bath through as in large quantity. As ex lained, the hya conduit extending below the surface thererogen bubbles in being 'viol ently detached l of, substantially as set forth. from the cathode-surfaces effect a very per- 2. The process of cleaning continuous mefect cleaning by stri ping off all forei nmat- 1 tallic strips, which consists in passing the ter therefrom. I fi iid in practice t at the strip as a cathode through an electrolytic socleaning effect thus secured is of a very supel lution opposed to an anode not attacked by rior kind, so that when a subsequent coating, the solution and =in'removing the strip from such as an electrical de osit of nickel, is apthe solution through a closed conduit, lead- .plied to the strip such eposit will be effect- I ing below the surface of the solution, substaned with great uniformity and adhesion and at 1 tially as set forth.

the same time is very homogeneous. Mani- I 3. The process of cleaning continuous mefestly with an apparatus such as described l tallic strips, which consists in assing the as the strip 3 slowly progresses through the l strip as a cathode through an al aline solusolution its surfaces will .be successively or tion opposed to a carbon anode and in rerogressively cleaned, so that the a paratus moving the stri from the solution through a ecomes a continuous one. At tlie same closed conduit eading below the surface of time since the strip leaves the solution by the solution, substantially as set forth.

passing through the tube 4 there is no danger This specification signed and witnessed this of 8.1111) ofntfhe fOIiSlgfiImQittGI' which may float 24th day of June, 1904.

ont e s ace 0 t e so ution contaminatin l a the cleaned surfaces. g THOS' EDISON Having now described my invention, what 3 Witnesses:

I claim as new therein, and desire to secure FRANK L. DYER,

by Letters Patent, is as follows: MINA C. MAOARTHUR. 

